问答题 Directions: You had a party at your home recently , but you unintentionally neglect to invite a close friend of yours, Victoria. Write a letter to 1) make an apology, and 2) explain how the mistake came about. Write your letter with no less than 100 words. Do not sign your name at the end of the letter. Use “Li Ming” instead. Do not write the address.

问答题 This principle, in fact, underlies all psychological treatment of children in difficulties with their development, and is the basis of work in child clinics.

单项选择题 The function of genetic testing is